Let's be realistic here, you aren't going to find another job that pays this well and leaves you alone so much.  You've got it better than anyone else you know in terms of total compensation for your hours invested. But why should it be so hard.  It's the same job more or less that it was 12 years ago, and 12 years ago you couldn't have been happier in your work.

Perhaps it's not the work's fault at all...maybe it is your lack of purpose.  Why are you here?

Is it your job's responsibility to give you purpose in your life?  Maybe for some people...but clearly you aren't or don't want to be only associated with work, right?

So, who are you then? 

Today the honest answer is "a bored middle aged middle income shlub with no goal to chase beyond surviving to retirement"

In dreams?

A fully free person empowered to chase any whim or hobby to its end. An avid reader and hiker and explorer, someone who could write their feelings without remorse or editing to appease the reader. You wake with the sun, fill a backpack and follow life wherever it is heading today.  You have an outlet for your ideas that compensates you fairly.

I'm not a bridge builder and I don't know how to gap this chasm. 

Why would you replace this job with one that wants more from you in return for less? What more could it give? Purpose...again.

Well, sorry bub - you aren't going to find purpose in a cubicle or on a laptop on your couch. 
Keep the easy road you are on, don't go hunting for the silvery road filled with treasure.

For now, find ways to lay on the beach and stay warm and read all the books.  Get your work done so nobody complains.

Take deep breaths, stretch, eat healthy, get outside, laugh laugh laugh (I know it is impossible).